Determining fluid rheological properties

ABSTRACT

Controlling a well injection operation, such as a well fracturing operation, includes identifying a flow characteristic of a fracturing fluid, identifying a flow characteristic of a base fluid used for forming the fracturing fluid, determining an amount of friction reduction change of the fracturing fluid, and adjusting the amount of friction reduction of the fracturing fluid to coincide with a selected friction reduction amount. Identifying a flow characteristic may be performed by a rheology measuring device including a measurement tube, a first pressure sensor disposed at a first position on the measurement tube, a second pressure sensor disposed at a second position on the measurement tube, a flow meter disposed at a third position along the measurement tube, a temperature sensor disposed at a fourth location along the measurement tube, and a control unit interconnected to the first and second pressure sensors, the flow meter, and the temperature sensor.

TECHNICAL FIELD

This disclosure relates to determining fluid rheological properties.

BACKGROUND

In oilfield applications, there are many instances where it is desirableto know the viscosity or rheological properties of a fluid. For example,a fracturing operation involves pumping a fracturing fluid into asubterranean zone in order to create fractures in the rock of thesubterranean zone. The fractures provide flow passages that conveyfluids between the subterranean zone and the wellbore. The distance thatthe fractures penetrate into the subterranean zone (i.e., fracturelength) is a function of, among other things, the pressure that can begenerated within or near the subterranean zone. Furthermore, thisfracture length is a also a function of flow rate into the subterraneanzone. To optimize pressure and flow rate at the subterranean zone, thefracturing fluid is typically injected rapidly into or near thesubterranean zone. Rapid injection has large associated costs, though,such as the amount of pumping power required to quickly inject thefracturing fluid. The pumping power may be reduced and the fracturingfluid may be introduced more quickly by altering (e.g., lowering) thefrictional drag characteristics of the fluid, such as with frictionreducing additives. The amount of some friction reducing additives mustbe carefully controlled to maintain the friction reduction of thefracturing fluid at a desired level. The width of the created fractureis function of the fluid viscosity of the fracturing fluid at thesubterranean zone. Gelling agents used to generate viscosity have costsand other undesirable effects. The fluid viscosity must be carefullycontrolled to maintain the viscosity at a desired level to optimizedesired effects (e.g., fracture width) while minimizing undesiredeffects (e.g., cost).

SUMMARY

The present disclosure relates to determining fluid rheologicalproperties for improving a fracturing operation. One aspect encompassesa method for controlling a well injection operation. According to themethod, a flow characteristic of a fracturing fluid is identified, and aflow characteristic of a base fluid used for forming the fracturingfluid is identified. The method also encompasses determining an amountof friction reduction change of the fracturing fluid in relation to theflow characteristic of the fracturing fluid and the flow characteristicof the base fluid and adjusting the amount of friction reduction of thefracturing fluid to coincide with a selected friction reduction amount.

Another aspect encompasses a rheology measuring device. The rheologymeasuring device includes a measurement tube, a first pressure sensor isdisposed at a first position on the measurement tube, and a secondpressure sensor disposed at a second position on the measurement tube. Aflow meter is disposed at a third position along the measurement tube.The rheology measuring device also includes a temperature sensordisposed at a fourth location along the measurement tube and a controlunit interconnected to the first and second pressure sensors, the flowmeter, and the temperature sensor.

Another aspect encompasses a method for measuring a rheological propertyof a fluid. The method encompasses passing a fluid flow through ameasurement tube at a selected flow characteristic. The pressure of thefluid flow is determined at a first location along the measurement tube.Additionally, a pressure of the fluid flow is determined at a secondlocation along the measurement tube. A pressure difference of the fluidflow is determined between the first and second locations, and aviscosity of the fluid is determined based on the pressure difference.

The various aspects can include one or more of the following features.Identifying the flow characteristic of the fracturing fluid can includemeasuring a pressure change of a flow of the fracturing fluid at aselected flow rate. Measuring the pressure change of the flow of thefracturing fluid at the selected flow rate can include measuring thepressure change of the flow of the fracturing fluid at a flow ratecorresponding to a flow rate at which the fracturing fluid is beinginjected into the well. Identifying the flow characteristic of thefracturing fluid can include measuring a pressure change of a flow ofthe fracturing fluid at one of a selected shear rate, Reynolds Number,fluid velocity, flow rate, flow noise, or other descriptor thatcharacterizes the flow. Identifying the flow characteristic of the basefluid can include measuring a pressure change of a flow of the basefluid at one of a selected shear rate, Reynolds Number, fluid velocity,flow rate, flow noise, or other descriptor that characterizes the flow,and measuring the pressure change of the flow of the base fluid at theselected flow rate can include measuring the pressure change of the flowof the base fluid at a flow rate corresponding to a flow rate at whichthe fracturing fluid is being injected into the well. Identifying theflow characteristic of the base fluid used for forming the fracturingfluid can include referencing a compilation of flow property data of thebase fluid. Additionally, referencing a compilation of the flow propertydata of the base fluid can include selecting from a plurality ofpredetermined flow characteristic data a flow characteristic value ofthe base fluid corresponding to a flow rate at which the fracturingfluid is being injected into the well. Referencing a compilation of theflow property data of the base fluid can include selecting from aplurality of predetermined flow characteristic data a flowcharacteristic value of the base fluid at one of a selected shear rate,Reynolds Number, flow velocity, flow rate, flow noise, or otherdescriptor that characterizes the flow.

The various aspects can also include one or more of the followingfeatures. Determining the amount of friction reduction change of thefracturing fluid can include comparing a friction indicator of the basefluid to a friction indicator of the fracturing fluid. Comparing thefriction indicator of the base fluid to the friction indicator of thefracturing fluid can include comparing a predetermined pressure changeof a flow of the base fluid at one of a selected shear rate, ReynoldsNumber, fluid velocity, flow rate, flow noise or other descriptor thatcharacterizes the flow to a pressure change of a flow of the fracturingfluid at a corresponding one of a selected shear rate, Reynolds Number,fluid velocity, flow rate, flow noise, or other descriptor thatcharacterizes the flow. Comparing the friction indicator of the basefluid to the friction indicator of the fracturing fluid may includecomparing a pressure change of a flow of the base fluid at one of aselected shear rate, Reynolds Number, fluid velocity, flow rate, flownoise or other descriptor that characterizes the flow to a correspondingone of a selected shear rate, Reynolds Number, fluid velocity, flowrate, flow noise, or other descriptor that characterizes the flow.

Further, the various aspects can include one or more of the followingfeatures. A portion of the measurement tube may be curved, and thecurved portion of the measurement tube may include 1.5 loops. Therheology measurement device may also include an inlet tube and an outlettube, wherein internal diameters of the inlet tube, the outlet tube, andthe measurement tube are the same. A length of the inlet tube maycorrespond to a length for establishing a laminar flow of a fluidflowing therein at the first position and wherein a length of the outlettube corresponds to a length for establishing a laminar flow of a fluidflowing therein at the second position. A curved portion of themeasurement tube can include 1.5 loops. The first and second pressuresensors can include a pressure transducer operable to measure a pressuredifference of a fluid flowing through the measurement tube. The controlunit can determine a rheological property of a fluid flowing through themeasurement tube. The rheology measurement device can also include apump operable to pump a fluid through the measurement tube. The controlunit can be coupled to the first and second pressure sensors, the flowmeter, the temperature sensor, and the pump. The control unit candetermine a fluid flow rate through the measurement tube via the flowmeter and control the pump to establish a flow rate of the fluid throughthe measurement tube at a selected flow rate. The flow meter can be oneof an electromagnetic flow meter, a coriolis flow meter, an ultrasonicflow meter, a vortex flow meter, a turbine flow meter, or positivedisplacement flow meter. Additionally, the various aspects can control aflow rate of the fluid flow through the measurement tube to maintain theselected control characteristic, and the selected flow characteristiccan be a shear rate.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is an example system for monitoring and controlling a compositionof a fracturing fluid;

FIG. 2 is a detail view of a portion of the system of FIG. 1;

FIG. 3 is a graph indicating friction reduction of a fluid with changingadditive concentration;

FIG. 4 is a schematic view of an example rheology measuring device;

FIGS. 5A and 5B illustrate different views of an example rheologymeasuring device;

FIG. 6 shows an example mobile fracturing apparatus incorporating therheology measuring device; and

FIG. 7 is an example schematic diagram of an operating configuration ofa rheology measuring device.

DETAILED DESCRIPTION

FIG. 1 shows an example system 10 for monitoring and controllingproperties of a fracturing fluid used in a fracturing operation. Asshown, the fracturing fluid is injected into a wellbore 20 formed belowa surface 30. The wellbore 20 extends to a subterranean zone 40.Although the wellbore 20 is shown as penetrating the subterranean zone40, the wellbore 20 may extend through or terminate near thesubterranean zone 40. The system 10 also includes one or more storagetanks 50 containing a base fluid. The base fluid may be formed from acombination of water and a gel polymer. The base fluid may be used toform the fracturing fluid. The system 10 further includes a blenderapparatus 60 for blending the base fluid and a friction reducer 70 andother optional additives, such as a proppant 80. The system may alsoinclude a measurement and control module 90 for monitoring a conditionof the base fluid and a condition of the fracturing fluid.

At a high level, the base fluid 100 enters the blender apparatus 60where it is combined with an amount of the friction reducer 70 and/orproppant 80. Once combined, the resulting fracturing fluid 110, exitsthe blender apparatus 60 and is pumped, via a pump 61, through a tubingstring 120 for injection into the wellbore 20, for example. Thefracturing fluid 110 exits the tubing string 120 in or near thesubterranean zone 40 where the fracturing fluid 110, under pressure,enters and produces fractures (interchangeably referred to as a fracturenetwork) 130 in the rock of the subterranean zone. A blending portion140 of the system 10 is described in more detail below.

FIG. 2 shows the blending portion 140 of the system 10 according to oneimplementation. As explained above, the base fluid 100 is delivered tothe blender apparatus 60 from the storage tank 50. A portion 160 of thebase fluid 100 is diverted via a conduit 170, and a pressure change,ΔP_(C), (i.e., a fluid pressure change along a specified flow distance)of the portion 160 is measured by a first pressure measurementinstrument 175. Some examples of the first pressure measurementinstrument 175 include the Rosemount 3051 series differential pressuretransducers, the Endress+Hauser PMD7X series and FMD7X seriesdifferential pressure transducers, as well as other devices formeasuring pressure. The first pressure measurement instrument 175 mayinclude two independent, non-differential pressure transducers providedon the conduit 170 coupled to a processing unit. The processing unit maybe operable to determine a pressure difference from a pressuremeasurement of each of the transducers and output the pressuredifference. Additional examples of the first pressure measurementinstrument 175 include the Rosemount 3051 series non-differentialpressure transducers and the Endress+Hauser PMP7X series and PMC7Xseries non-differential pressure transducers. A first flow controldevice 180 is also disposed along the conduit 170 for controlling a flowrate of the portion 160 at a selected level. As used herein, flow ratemay include volumetric or mass flow rate. Some examples of flow controldevice 180 include a pump, a control valve, or other devices forcontrolling flow. An example pump may be a positive displacementmetering pump. The remainder of the base fluid 100 enters the blenderapparatus 60 and is combined with an amount of friction reducer 70and/or proppant 80. The friction reducer 70 is conveyed to the blenderapparatus 60 via a conduit 190, and the proppant 80 is conveyed to theblender apparatus 60 via a conduit 200. According to someimplementations, the friction reducer 70 is operable to reduce thepressure loss of the fracturing fluid 110 over a range of concentrationof the friction reducer 70. Examples of friction reducers 70 include,but are not limited to, anionic and cationiic polyacrylamide polymers,guar, hydroxypropyl guar (HPG), carboxymethyl hydroxypropyl guar,hydroxyethylcellulose, and Xanthan. The friction reductioncharacteristics of an example friction reducer are discussed in moredetail below with reference to FIG. 3. Additive control devices 210 and220 are disposed along the conduits 190 and 200, respectively, forcontrolling a flow of the friction reducer and proppant. Some examplesof additive control devices include a flow control valve, measuringscrew, or other device. Although not illustrated, other additives can beadded into the blender apparatus 60 for incorporation with the basefluid. Some examples of other additives can include borate, titanate,and zirconate cross linking agents, biocides, pH control agents such asformic acid or caustic soda, enzymatic and oxidizing breakers, claystabilizers or other additives. The other additives may be added in lieuof or in combination with the friction reducer 70 and/or proppant 80.Although FIG. 2 illustrates one example location of conduit 170, theconduit 170 may be provided at other locations to draw off a portion ofthe base fluid 100. That is, conduit 170 may be located to draw off aportion of the base fluid 100 prior to the addition of, for example, theproppant 80, the friction reducer 70, or other additives that may besubsequently added to the base fluid.

The fracturing fluid 110 exits the blender apparatus 60. A portion 230of the fracturing fluid 110 is diverted into a conduit 240 and ismeasured by a second pressure measurement instrument 250. Some examplesof pressure measurement instrument 250 include a Rosemount 3051 seriesdifferential pressure transducer, a Endress+Hauser PMD7X series andFMD7X series differential pressure transducer, as well as other devicesfor measuring pressure. The second pressure measurement instrument 250may also include two independent, non-differential pressure transducersprovided on conduit 240 coupled to a processing unit. The processingunit may be operable to determine a pressure difference from a pressuremeasurement of each of the transducers and output the pressuredifference. Additional examples of the first pressure measurementinstrument 250 include the Rosemount 3051 series non-differentialpressure transducers and the Endress+Hauser PMP7X series and PMC7Xseries non-differential pressure transducers. The second pressuremeasurement instrument 250 measures a pressure change, ΔP_(F), e.g., afluid pressure change along a specified flow distance, of the portion230. The conduit 240 also includes a second flow control device 260, forcontrolling a flow rate of the portion 230 at a selected level. Someexamples of the flow control device 260 include a pump, a control valve,or other devices for controlling flow. An example pump used as the flowcontrol device 260 may include a positive displacement metering pump.The remainder of the fracturing fluid 110 is conveyed to the wellbore 20and injected into or near the subterranean zone 40 to form fractures130.

The measured pressure changes, ΔP_(F) and ΔP_(C), of the portions 160and 230 are transmitted to a control unit 270. The control unit 270determines a friction reduction value which corresponds to a frictionreduction ratio (“FRR”) of ΔP_(F) to ΔP_(C) or vice versa. The FRRprovides a comparison of the friction pressure drop of the base fluid100 without additives added at blender apparatus 60 and the fracturingfluid 110. Consequently, this ratio may be used to determine an amountof friction reduction of the fracturing fluid 110 has been achieved.Once the ratio is determined, the ratio is compared to a selected targetratio. According to some implementations, the target FRR is selected toprovide the greatest amount of friction reduction of the fracturingfluid relative to the base fluid that can be achieved with theparticular friction reducer additive.

The addition of a friction reducer to a liquid, such as the base fluid100, may result in fluid friction reduction over a concentration rangeof fluid reducer. However, the viscosity of the fluid may appear toincrease as the fluid friction decreases. The apparent discrepancy maybe the result of the flow profile established when fluid measurementsare taken, for example, a laminar flow profile versus a turbulent flowprofile. For example, measurement of a fluid having a dynamic viscosityof 3 cP at a flow rate of 511 scc⁻¹, for example, corresponds to aReynolds Number (N_(re)) of approximately 1000, which indicates alaminar flow regime. At the same flow rate, the flow regime would remainlaminar as the viscosity increases. However, when a fluid used in afracturing operation is measured under the same or approximately thesame conditions that exist during the fracturing operation, e.g., thesame flow rate that the fluid is flowing through the well tubulars, ameasured friction pressure of the fluid is reduced. For example, anexample fracturing operation may involve flowing a fracturing fluidthrough a 2.441 inch diameter well tubular at a rate of 20 bbl/min. Thefracturing fluid may have a dynamic viscosity of 24 cP (when measured at511 scc⁻¹ and having a Reynolds Number of 127 (laminar)). When measuredunder the above fracturing conditions, the fracturing fluid may have aReynolds Number of approximately 100,000, which is a highly turbulentflow. The friction reducer added to the fracturing fluid may includelong-chain polymers. At this flow rate, the friction reduction caused bythe long-chain polymers is noticeable while the friction increase causedby viscous effects are negligible. Thus, a fluid having a high dynamicviscosity when measured under a laminar flow regime may have noticeablefriction reduction under fracture operation conditions due to the addedfriction reducer. At increased concentrations of the friction reducer,the viscous effects may offset the friction reduction causing thefluid's friction reduction ratio increase, as shown in FIG. 3.

FIG. 3 is a graph 280 of the friction reduction behavior of an examplefracturing fluid as a function of the amount of added example frictionreducer. Concentration range 290 (between points A and B) is theconcentration of the additive that increases the friction reductionratio of the fracturing fluid. The concentration range of the additivebeyond Point B causes the viscosity of the fracturing fluid to increase.The concentration range of the additive below Point A causes little tono change in the friction of the fracturing fluid. Thus, during afracturing operation, a frictional pressure drop of the fracturing fluidcan be decreased if the additive concentration is maintained within therange 290. As a result, the amount of power required to pump the fluidmay be reduced.

Referring again to FIG. 2, the selected target ratio may be selected soas to correspond to a fracturing fluid having a concentration of one ormore additives resulting in the lowest possible frictional pressure dropas illustrated, for example, in FIG. 3, described above. The selectedtarget FRR is determined based on different considerations which may ormay not be unique to a particular fracture operation, such as one ormore of the chemical composition of the base fluid, the additive beingused, the amount of other additives added to the fracturing fluid, theequipment being used to perform the fracturing operation, the nature ofthe subterranean zone, the strata adjacent to or otherwise proximate tothe subterranean zone, or other considerations. Once the measured FRR iscompared with the selected target FRR, the control unit 270 determineswhether any changes to the amount of one or more additives should bemade in order to maintain the fracturing fluid at a desired FRR. Toeffect a change the control unit 270 may transmit a signal to one ormore of the additive control devices 210 or 220 to adjust addition ofthe respective additives. Although not shown, the control unit 270 mayalso transmit signals to other control devices that control the additionof other additives that may be added to the fracturing fluid.

If the fracturing fluid behaves as a non-Newtonian fluid, such asbecause of the addition of some additives, the viscosity of thefracturing fluid is shear rate dependent. That is, the viscosity of thefracturing fluid changes depending upon the fracturing fluid's shearrate. The shear rate may change depending upon, for example, thegeometry of the pipe, e.g., inner pipe diameter, through which a fluidflows, the path of the flow, the velocity of the fluid, etc.

Thus, according to one implementation, the flow characteristics of thefracturing fluid down the wellbore 20 (e.g., tubing string 120) and/orin or near the subterranean zone 40 are identified. The flow, Q₁ (shownin FIG. 1), of the fracturing fluid within the tubing string 120 and/orin or near the subterranean zone 40 can be determined, for example byestimating or by measurement. The flow, Q₂, of the fracturing fluidwithin the conduit 240 can be made to correspond. That is, the flow rateQ₂ may be made to model the flow of the Q₁. For example, the flow Q₁ ofthe fracturing fluid through the tubing string 120 may be characterizedby determining or approximating a shear rate, Reynolds Number, or otherdescriptor that characterizes the flow. The flow Q₂ within the conduit240 can be created to correspond to that of Q₁ for example by matchingor making a corresponding shear rate, Reynolds Number, or otherdescriptor that characterizes the flow to the flow Q₁ within the tubingstring 120. Further, in a fracturing operation, the fracturing fluidinjected into a wellbore is generally turbulent. Thus, Q₁ may be aturbulent flow. Accordingly, the flow Q₂ may also be defined to be aturbulent flow. However, according to other implementations, Q₁ may be alaminar flow, and, as such, Q₂ may be defined as a laminar flow.

Referring again to the implementation shown in FIG. 2, the flow rate ofQ₂ through the conduit 240 having a shear rate, Reynolds Number, orother descriptor that characterizes the flow corresponding to the flowQ₁ through the tubing string 120 may be determined. The modeled flow Q₂through to the conduit 240 may also be applied to the flow of the basefluid through the conduit 170 (also labeled Q₂ in FIG. 2). The flows Q₂within the conduits 170 and 240 may be maintained by the flow controldevices 180 and 260, respectively. For example, the flow control devices180 and 260 may include a flow meter for measuring the flow rate and apump or throttling valve for adjusting the flow rates to match a targetflow rate corresponding to the modeled flow. According to someimplementations, the flow control devices 180 and 260 may be selfcontained, i.e., the measurement and adjustment of the flows through theconduits 170 and 240 are entirely controlled by the flow control devices180 and 260. According to other implementations, the flow ratemeasurements from the flow control devices 180 and 260 may betransmitted to the control unit 270 and control signals 300 and 310 maybe transmitted to the flow control devices 180 and 260 to adjust thefluid flows. As explained above, maintaining the flows Q₂ includesmaintaining the flows Q₂ at a turbulent flow rate, although the flows Q₂may be maintained at other flow rates, such as a laminar flow rate.Consequently, the flows Q₂ may be maintained at either a turbulent flowcondition, laminar flow condition, or other desired flow condition.

Once the flow Q₂ is established in the conduits 170 and 240, the ΔP_(F)and ΔP_(C) may be measured, and a FRR may be determined. The controlunit 270 compares the target FRR and the measured FRR and adjusts theamount of additives to the base fluid to provide the fracturing fluidwith the desired friction reduction.

According to another implementation, the FRR is determined at a selectedshear rate, Reynolds Number, or other descriptor that characterizes theflow of both the base fluid 100 and the fracturing fluid 110. That is,the FRR is determined by measuring ΔP_(F) and ΔP_(C) at a common flowdescriptor value. For example, a shear rate of 10,000 scc⁻¹ or aReynolds Number of 100,000. By determining the FRR at a selected flowdescriptor, the tubing string geometry, such as the inner diameter ofthe tubing, need not be known. Accordingly, the flows of portions 160and 230 through the conduits 170 and 240, respectively, are adjusteduntil the flows possess the selected flow descriptor. For example, thefluid properties of the base fluid 100 and the fracturing fluid 110 maybe known, including the flow descriptor value of the fluids at a givenflow rate and may be provided in one or more sets of data. For thefracturing fluid 110, numerous sets of data may be included forfracturing fluids having different compositions. Depending upon theamount and type(s) of additive(s) being applied one or more times duringthe fracturing operation, the appropriate data set may be referencedand, thus, the appropriate data may be utilized. Because the compositionof the fracturing fluid 110 may change during the fracturing operation,the data set being used may change.

Consequently, the flow rates, Q₂, of portions 160 and 230 may beadjusted to correspond with a flow rate having the desired flowdescriptor value. The flow rates of the portions 160 and 230 may beadjusted manually or automatically via the flow control devices 180 and260. For automatic control, the control unit 270 may include the datasets for the fracturing fluid 110 and the base fluid 100 listing flowrates with the corresponding shear rates. The control unit 270 may thenadjust the flows of portions 160 and 230 to a flow rate having thedesired flow descriptor values using the flow control devices 180 and260.

When the flows of portions 160 and 230 have been adjusted to a desiredflow rate, the ΔP_(F) and ΔP_(C) may be measured and the FRR determined.Thereafter, the control unit 270 may transmit signals to the additivecontrol devices 210 and 220 to achieve the target FRR. Once the portions160 and 230 have been measured, the fluids may be returned to the baseand fracturing fluids 100 and 110, respectively, or otherwise dischargedfrom the system 10.

According to another implementation, the conduit 170, the first pressuremeasurement instrument 175, aid the flow control device 180 may beeliminated and replaced with measured or simulated data for the basefluid 100. For example, the base fluid 100 may remain relativelyunchanged during the fracturing operation. Consequently, the compositionand properties of the base fluid 100 remain relatively constant. Assuch, the properties of the base fluid 100 may be determined by testingand/or simulation performed prior to the fracturing operation. Once theproperties of the base fluid 100, such as the ΔP_(C) and viscosity ofthe base fluid at different shear rates and velocities are determined,the information (referred to hereinafter as “fluid propertyinformation”) may be recorded and stored for subsequent use. Therefore,at a fracturing operation, the stored fluid property information of thebase fluid 100 may be manually or automatically applied to determine theFRR. The fluid property information of the base fluid 100 may be storedand/or applied by the control system 270 to adjust the addition of theadditives for maintaining the viscosity of the fracturing fluid 110 at adesired level.

A further implementation combines features of the above implementationsin that the conduit 170, the first pressure measurement instrument 175,and the flow control device 180 may be eliminated and replaced withmeasured and/or simulated data fluid property information for the basefluid 100, and the FRR may be determined at a selected flow descriptorvalue, thus eliminating the need to know the flow characteristics of thefracturing fluid 110 through the tubing string 120. As such, the flowrate of portion 230 may be controlled, Such as with the flow controldevice 260, to correspond to a selected flow descriptor value. Further,stored data of the base fluid may be referenced to identify the ΔP_(C)corresponding to the selected flow descriptor value.

As a result, the flow rate of the portion 230 through conduit 240 may beadjusted to correspond to the selected flow descriptor value. Theresulting ΔP_(F) may then be determined. Also, the ΔP_(C) may beidentified by referencing the fluid property information for the basefluid. Thus, the FRR may be determined aid the amount of additivesadjusted, if needed, to achieve the selected friction reduction of thefracturing fluid 110.

The first pressure measurement instrument 175 and the first flow controldevice 180 may form a portion of a rheology measurement device (“RMD”)320, and the second pressure measurement instrument 250 and the secondflow control device 260 may form a portion of an RMD 330. According toother implementations, one or more of the RMDs 320 the 330 may bedisposed in the system 10 to directly measure one or more of the basefluid 100 and the fracturing fluid 110.

The RMDs 320 and 330 may be substantially similar. According to someimplementations, an RMD 400, illustrated in FIGS. 4, 5A, and 5B, may beused as the RMDs 320 and 330. For simplicity purposes, the RMD 400 shownin FIGS. 4, 5A, and 5B will be used throughout the remainder of thedisclosure for explaining the construction and operation of the RMD,according to some implementations, although it will be understood thatthe description of RMD 400 may also apply to RMD 320 and 330.

A schematic view of the RMD 400 is shown in FIG. 4. The RMD 400 includesa measurement tube 410, having an inlet 420 and an outlet 430; an inlettube 435; and outlet tube 437; a differential pressure sensor 440 havinga first pressure sensor 450 disposed at a first location 460 of themeasurement tube 410 and a second pressure sensor 470 disposed at asecond location 480 of the measurement tube 410; a flow meter 490, and atemperature sensor 500. According to some implementations, the flowmeter 490 may be a coriolis flow meter, electromagnetic flow meter(interchangeably referred to as “magnetic flow meter”), vortex flowmeter, turbine flow meter, or positive displacement flow meter.According to some implementations, a coriolis flow meter may be astraight or bent tube coriolis flow meter. Additionally, a flow meter orother instrumentation that determines fluid flow properties based on aflow noise or noise signal generated by the fluid may also be used. Forexample, such instrumentation may include a flow meter, a microphone, orpressure transducer optimized to detect a noise signal corresponding toturbulence of the fluid flow. Example flow meters may include anelectromagnetic flow meter or an ultrasonic flow meter. Such flow metersmay provide a bulk flow rate as well as additional information regardinghigher frequency variations in flow rate caused by turbulence. The RMD400 may also include a pump 510 that may be utilized to adjust a flow ofthe fluid being measured passing through the measurement tube 410. Thepump 510 may be disposed in or attached to the inlet pipe. For example,the pump may be driven by a motor 515, such as a 24 volt DC motor, a 110volt AC motor, a hydraulic motor, a pneumatic motor, or other knowndrive mechanisms. Additionally, the RMD 400 also includes a control unit520 for monitoring, collecting data, and/or controlling one or moreoperations of the RMD 400. The components of the RMD 400 may be sized orarranged to occupy a small volume for convenient transportation and maybe attached directly or indirectly to a chassis 485 (shown in FIGS. 5Aand 5B). For example, the RMD 400 may be incorporated into a mobilefracturing apparatus 525, such as the mobile fracturing vehicle shown inFIG. 6. As shown, the RMD 400 is disposed on the mobile fracturingapparatus 525, such as below the control platform.

The control unit 520 may be implemented in digital electronic circuitry,or in computer software, firmware, or hardware, including the structuralmeans disclosed in this specification and structural equivalentsthereof, or in combinations of them. The control unit 520 can beimplemented as one or more computer program products, i.e., one or morecomputer programs tangibly embodied in an information carrier, e.g., ina machine readable storage device or in a propagated signal, forexecution by, or to control the operation of, data processing apparatus,e.g., a programmable processor, a computer, or multiple computers. Acomputer program (also known as a program, software, softwareapplication, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile. A program can be stored in a portion of a file that holds otherprograms or data, in a single file dedicated to the program in question,or in multiple coordinated files (e.g., files that store one or moremodules, sub programs, or portions of code). A computer program can bedeployed to be executed on one computer or on multiple computers at onesite or distributed across multiple sites and interconnected by acommunication network.

The control unit 520 may include one or more processors that executeinstructions and manipulates data to perform the operations and may be,for example, a central processing unit (CPU), a blade, an applicationspecific integrated circuit (ASIC), or a field-programmable gate array(FPGA). Processors suitable for the execution of a computer programinclude, by way of example, both general and special purposemicroprocessors, and any one or more processors of any kind of digitalcomputer. Generally, the processor will receive instructions and datafrom ROM or RAM or both. The essential elements of a computer are aprocessor for executing instructions and one or more memory devices forstoring instructions and data. Generally, a computer will also include,or be operatively coupled to receive data from or transfer data to, orboth, one or more mass storage devices for storing data, e.g., magnetic,magneto optical disks, or optical disks. Information carriers suitablefor embodying computer program instructions and data include all formsof nonvolatile memory, including by way of example semiconductor memorydevices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks,e.g., internal hard disks or removable disks; magneto optical disks; andCD ROM and DVD-ROM disks. The processor and the memory can besupplemented by, or incorporated in, special purpose logic circuitry.

The control unit 520 may also include one or more memory devices. Eachmemory device may include any memory or database module and may take theform of volatile or non-volatile memory including, without limitation,magnetic media, optical media, random access memory (RAM), read-onlymemory (ROM), removable media, or any other suitable local or remotememory component. The one or more memory devices may include applicationdata for one or more applications, as well as data involving VPNapplications or services, firewall policies, a security or access log,print or other reporting files, HTML files or templates, related orunrelated software applications or sub-systems, and others.Consequently, the memory may also be considered a repository of data,such as a local data repository for one or more applications.

The control unit 520 may also include an output device, such as adisplay device, e.g., a cathode ray tube (“CRT”) or LCD (liquid crystaldisplay) monitor, for displaying information to the user as well as aninput device, such as a keyboard and a pointing device, e.g., a mouse ora trackball, by which the user can provide input to the computer. Otherkinds of devices can be used to provide for interaction with a user aswell to provide the user with feedback. For example, feedback providedto the user can be any form of sensory feedback, e.g., visual feedback,auditory feedback, or tactile feedback; and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The application may be any application, program, module, process, orother software that may utilize, change, delete, generate, or isotherwise associated with the data and/or information associated withone or more control operations of the RMD 400. “Software” may includesoftware, firmware, wired or programmed hardware, or any combinationthereof as appropriate. Indeed, the application may be written ordescribed in any appropriate computer language including C, C++, Java,Visual Basic, assembler, Perl, any suitable version of 4GL, as well asothers. It will be understood that, while the application may includenumerous sub-modules, the application may instead be a singlemulti-tasked module that implements the various features andfunctionality through various objects, methods, or other processes.Further, while the application may be internal to control unit 520, oneor more processes associated with the application may be stored,referenced, or executed remotely (e.g., via a wired or wirelessconnection). For example, a portion of the application may be a webservice that is remotely called, while another portion of theapplication may be an interface object bundled for processing at remoteclient. Moreover, the application may be a child or sub-module ofanother software module or application. Indeed, the application may be ahosted solution that allows multiple parties in different portions ofthe process to perform the respective processing.

At a high level, the RMD 400 uses a closed-loop flow control to adjust aflow of the fluid passing through the measurement tube 410. The pump 510may be used to maintain the flow at a selected level. A pressuredifferential, ΔP, of the fluid is measured between the first and secondlocations 460 and 480. The ΔP and flow rate are used by the control unit520 to determine a viscosity of the fluid or other rheologicalproperties, such as pressure drop versus flow rate, pressure drop versusshear rate, pressure drop versus a measure of turbulence (e.g., ReynoldsNumber), and the fluid-specific descriptive coefficients in fluidmodels, such as the Power Law model. The temperature of the fluid,measured by the temperature sensor 500, is used to provide informationabout the fluid when a ΔP measurement is made. The rheologicalproperties of most fluids change with temperature. Thus, it is common tomake standardized measurements referenced to a particular temperature,for example, 25° Celsius. Temperature sensor 500 can be used with anappropriate fluid model to adjust a measurement from the temperaturemeasured to a reference temperature or to another temperature. Thus, thetemperature measurement, such as a temperature measurement made by thetemperature sensor 500, may be used to compare fluid propertiesdetermined at the measured temperature to a standard referencedetermined at a different temperature or extrapolate the measuredproperties out to a different temperature. The conversion may beaccomplished with an appropriate fluid model. Additionally, viscositymeasurements are temperature sensitive, and, in some cases, a one degreeFahrenheit change in temperature can correspond to a two percentvariance in the viscosity. Therefore, it is important to measure afluid's temperature at location close in proximity to where the fluid'sproperties are measured. Further, the control unit 520 may be operableto output data 522, such as calculated data or measurement data, e.g.,viscosity, ΔP, temperature, and flow rate. The control unit 520 may alsobe operable to accept programming or other inputs, such as a flow ratesetpoint 524.

The RMD 400 provides for a stable platform with the capability ofrepeatable friction reduction measurement or viscosity measurementresults. Additionally, according to one implementation, the latency ofobtaining a viscosity measurement is approximately five seconds, e.g.,the travel time of the fluid between the first location 460 and thesecond location 480. Further, the RMD 400 is capable of measuring 15 to20 times more fluid than presently available systems.

RMDs within the scope of the present disclosure may be used to determineviscosity at a laminar flow rate as well as measure friction reductionof a fluid at a turbulent flow rate. Thus, a fluid may be passed througha measurement tube of the RMD at a flow rate corresponding to laminarflow, and optionally controlled to maintain such a flow rate, to measureviscosity. Other desired rheological properties may also be determined.Also, a fluid may be passed through the flow measurement tube of the RMDat a turbulent flow rate, and optionally controlled to maintain such aflow rate, to measure friction reduction. Similarly, other rheologicalproperties may also be determined.

According to one implementation, the measurement tube 410 is formed from316L stainless steel having an outer diameter of 0.375 inches and aninner diameter of approximately 0.277 inches, and the measurement tube410 has a length of approximately 72 inches. The measurement tube 410may also include an entrance length 530, i.e., a length of themeasurement tube 410 between the inlet 420 and the first location 460,of approximately 12 inches and an exit length 540, i.e., the length ofthe measurement tube 410 between the second location 480 and the outlet430 of approximately 6 inches. The entrance length 530 and exit length540 may be selected to establish laminar flow, for example, fullydeveloped laminar flow. Further, the entrance length 530 and exit length540 may have lengths different than those described above for differentimplementations. A bend geometry 542 of approximately 1.5 loops extendsbetween the first location 460 and the second location 480. The 1.5loops have a bend diameter of approximately 12.6 inches. As such, thefluid enters and exits a common side of the RMD 400. Moreover, theinternal diameters of the measurement tube 410, the inlet tube 435, andthe outlet tube 437 may be the same, which may produce less turbulenceand provide a more uniform laminar flow passing through the RMD 400.Additionally, the 1.5 loops may smooth the transition between turbulentand laminar flow thus enabling improved determination of fluid viscosityat lower viscosities when using simple calculation methods.

Although one implementation is described above, other implementationsare within the scope of the present disclosure. For example, RMDs havingdifferent entrance and exit lengths and different bend diameters arealso within the scope of the present disclosure. Further, according tosome implementations, the measurement tube does not include a bend. Thatis, according to some implementations, the measurement tube is straight.

According to one implementation, the differential pressure sensor 440may be a Rosemount model 3051C, produced by Rosemount Inc. of 8200Market Boulevard, Chanhassen, Minn. 55317, with PI Component fluidisolators. Alternatively, the differential pressure sensor 440 may be anEndress+Hauser model PMD75, produced by Endress+Hauser, Inc. of 2350Endress Place, Greenwood, Ind. 46143-9772, with ITT Conoflow fluidisolators produced by ITT Conoflow of 5154 Hwy. 78, St. George, S.C.29477. Also the flow meter 490 may be a Rosemount model 4711 with amodel 8712D transmitter or a Rosemount model 8711 with a model 8732Ctransmitter, both of which are produced by Rosemont, Inc. Thetemperature sensor 500 may be a Pyromation model R1T185, 100 ohmresistance temperature detector (RTD) produced by Pyromation, Inc. of5211 Industrial Road, Fort Wayne, Ind. 46825 or an Endress+Hauser modelTSM470G produced by Endress+Hauser, Inc.

The pump 510 may be a progressive cavity pump, such as a Netzsch modelNM008BY02S1B produced by Netzsch, Inc., of 119 Pickering Way Exton, Pa.,19341; a Seepex model MD 003-12/A6-A7-A7-H0-GA-X (X=0820, 11H0, 163)produced by Seepex, Inc., of 511 Speedway Drive, Enon, Ohio 45323; or aSeepex model MD 003-12/A6-A7-A7-H0-GA-X (X=04XX, 0802, 11H0, 163, 22XX)produced by Seepex, Inc. The pump 510 may be coupled to motor 515, suchas Leeson model C4D17NK10C (catalog number 108051), ½ hp, totallyenclosed, non-vented, 24 volt DC electric motor produced by LeesonElectric Corporation of 2100 Washington Street, Grafton, Wis. 53024-0241or a Baldor model CDP 3430-V24 produced by Baldor Electric Company of5711 R. S. Borehaimi, Jr. Street, Fort Smith, Ariz. 72901.

The pump 510 may include run-dry protection to prevent damage to thepump 510 should a run-dry condition occur. According to someimplementation, the run-dry protection may include a level switchinstalled in a cross on a suction line (not shown) of the pump 510. If afluid level is above the level switch, the level switch closes a circuitto the motor controller, and the pump 510 is operable. If a fluid levelis below the level switch, the level switch breaks the circuit, stoppingthe pump 510. Consequently, the pump 510 may be protected from runningdry, i.e., without a fluid flow passing through the pump 510. Accordingto one implementation, the level switch may be an Endress+Hauser modelFTL-20 vibrating fork produced by Endress+Hauser, Inc.

According to some implementations, the RMD 400 is packaged as a singlemodule or as numerous separate modules. For example, the RMD 400 mayinclude a first module, a second module, and a third module. The modulesmay be connected via Storm electrical cables (produced by InterconnectSystems of 1400 Memorex Drive, Santa Clara, Calf. 95050) havingpolyurethane jackets, ¼ inch Parker Push-Lok® hose (produced by ParkerHannifin Corporation of 30240 Lakeland Boulevard, Wickliffe, Ohio44092), and fittings with 7/16-20 (size 4) JIC connections. Processfittings may be either yellow brass or 316L stainless steel for fluidcompatibility.

The first module may include the motor controller, control switches, andassociated connectors, relays, fuses, wires, etc., for controlling themotor 515. The motor controller may receive raw power and a 4 to 20 mAdrive signal from a control system, and a signal from the level switchfor the run-dry protection may also be received by the motor controller.The motor controller outputs regulated motor drive power and power forthe level switch. The first module may be enclosed to protect againstenvironmental hazards and electromagnetic interference.

The second module may include the pump 510, the motor operable to drivethe plump 510, the run-dry protection, an air vent, a motor cover, andassociated fittings and adaptors. The components may be arranged toreduce a total volume of the second module. The second module isoperable to deliver a flow of the fluid to the third module formeasurement.

The third module may include the measurement tube 410, the differentialpressure sensor 440, the flow meter 490, the temperature sensor 500, thecontrol unit 520, and associated piping, fittings, and hardware formounting the components. The components of the third module may bemounted on heavy gauge stainless steel and enclosed with a sheet-metalcover. The third module may also include a vinyl cover. Electricalsignals to and from the various components may be transmitted through asingle, four pair, 18 gauge cable to the control unit 520.

The second and third modules may be located in close proximity to ensurea responsive viscosity measurement of the fluid, that is, to reduce atime delay between when the fluid is injected into the wellbore 20 andwhen a viscosity measurement is available. Once measured, the fluid maybe discharged into a tank or flow line. The flow meter 490 may receiveunregulated 24 volt DC power on one of the four pairs. The differentialpressure sensor 440 and the temperature sensor 500 may be loop-powered 4to 20 mA devices. The RMD 400 may also include a drain valve, such as onthe pump 510 to drain a fluid being measured by the RMD 400, such as thefracturing fluid 110 or portion 230 thereof, or any other fluid. Aportion of the measured fluid may collect in the RMD 400, such as thepump 510 after operation has stopped. Removal of the collectedfracturing fluid 110 may prevent damage to the RMD 400, for example,damage caused by freezing of the measured fluid. The RMD 400 may alsoinclude a pressure relief device to prevent over-pressuring systemcomponents.

The above examples are merely illustrative and should not be construedto limit the scope of the present disclosure. Accordingly, othercomponents and/or materials may be utilized to construct and/orimplement the RMD and/or system of the present disclosure.

FIG. 7 shows a schematic diagram of an operating configuration of theRMD 400 including a hydration tank 550 in communication with both thesecond module 560 and the third module 570. The first module is notshown. The fluid being measured, such as the fracturing fluid 110, maybe contained within the hydration tank 550 for a selected period oftime. For example, the fracturing fluid 110 may be delivered to thehydration tank 550 and stored therein a predetermined period of time toallow the fracturing fluid 110 sufficient time to hydrate. Thereafter, avalve, such as one or more of valves 580 and 590, is opened. The secondmodule 560 draws the fluid from the hydration tank 550 and, the fluid isdirected to the third module 570, where the viscosity is measured. Thefluid is then returned to the hydration tank 550 via a valve 600 that isnormally open during measuring. Valves 610 and 620, which are normallyclosed during operation of the second and third modules 570 and 580, maybe opened to purge fluid from the second module as well as conduits usedto convey fluid from the hydration tank 550 to the second module 560 andfrom the second module to the third module 570. A valve 630 may also beopened to purge the fluid from the conduit used to return fluid from thethird module 570 to the hydration tank 550.

FIG. 7 represents a configuration in which the fluid is being measured.However, according to another implementation, the fluid exiting thehydration tank 550 may be injected into a wellbore, such as wellbore 20,and a portion diverted to the third module 570 via the second module560. The measured fluid may then be returned to the hydration tank 550rather than being discarded.

In addition to determining a turbulent fluid's rheological properties,such as friction reduction, rheological properties of a laminar fluid,such as viscosity, may also be determined. According to someimplementations, determination of a measured fluid's viscosity may bedetermined by the RMD 320, 330, and 400 using the followingrelationships:

According to some implementations, the fracturing fluid 110 is anon-Newtonian fluid. Thus, the viscosity for the fracturing fluid 110may be determined by Equation 6, below, where γ_(W) is the shear rate atthe wall of the conduit conveying the fluid; γ is a particular shearrate (such as a selected shear rate); μ_(app) is an apparent viscosity;and μ is the viscosity at the particular shear rate γ. To solve Equation6, the following steps may be utilized: (The steps are described withreference to FIG. 4 for illustration purposes.)

Step 1: A flow rate, Q, must be established through the measurement tube410 at the desired Newtonian shear rate, γ.

Step 2: The pressure drop ΔP is measured, such as across locations 460and 480.

Step 3: An estimate of the viscosity is determined utilizing theEquation 1 (below), where R is the radius of the measurement tube 410, Lis the length of the measurement tube 410 between locations 460 and 480,Q is the flow rate of the fluid, and K₁ is the “K factor” or “meterfactor.”

Step 4: Estimate n (the power law coefficient) from the result of Step 3using an established relationship of n versus viscosity and temperature.

Step 5: Calculate an improved estimate using Equation 3 (below) and n,previously determined.

Step 6: Re-estimate n from the result of Step 5 using any establishedrelationship of n versus viscosity.

Step 7: Iterate Steps 5 and 6 until the viscosity converges withindesired tolerances.

Step 8: Calculate the actual shear rate (γ_(W)) using Equation 4.

Step 9: Calculate the final viscosity at the desired shear rate (γ)using Equation 6.

$\begin{matrix}{{\mu_{app} = {\frac{\pi\; R^{4}\Delta\; P}{8\; L\; Q} = K_{1}}}\frac{\Delta\; P}{Q}} & {{Equation}\mspace{14mu} 1} \\{{\overset{.}{\gamma}}_{w} = {\frac{4}{\pi\; R^{3}}Q}} & {{Equation}\mspace{14mu} 2} \\{{\mu_{app} = {{\frac{\pi\; R^{4}}{8\; L\; Q}\left( \frac{4n}{{3n} + 1} \right)} = K_{1}}}{\frac{\Delta\; P}{Q}\left( \frac{4n}{{3n} + 1} \right)}} & {{Equation}\mspace{14mu} 3} \\{\overset{.}{\gamma} = {\frac{4}{\pi\; R^{3}}\left( \frac{{3n} + 1}{4n} \right)Q}} & {{Equation}\mspace{14mu} 4} \\{\mu_{app} = {k\left( \overset{.}{\gamma} \right)}^{n - 1}} & {{Equation}\mspace{14mu} 5} \\{\mu = {\mu_{app}\left( \frac{\overset{.}{\gamma}}{\overset{.}{\gamma_{w}}} \right)}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

Determination of the viscosity varies with temperature of the measuredfluid. Thus, an additional fluid-specific adjustment may be performed toadjust the determined viscosity for a different temperature.Additionally, the calculated viscosity may be subject to correction,such as a rigorous, guar-based non-Newtonian fluid correction or asimple, guar-based non-Newtonian fluid correction. Most of thecorrection is performed to account for the bend geometry 542 of themeasurement tube 410.

The rigorous correction involves modifying Equation 1 as follows:

$\begin{matrix}{{\mu_{app} = {K_{morgan}K_{1}}}\frac{\Delta\; P}{Q}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

K_(morgan) is a linear adjustment to the calculated viscosity.K_(morgan) may be determined using Equations 8 and 9, shown below.

$\begin{matrix}{K_{morgan} = \frac{L}{L + {\alpha\; N_{Re}^{\beta}}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

According to some implementations, alpha (α) is equal to 0.0182, beta(β) is equal to 1.0678, and Re is the Reynolds number. The correctionfactor may vary from 0.80 to 0.99 for some tube geometries and measuredfluids having viscosities in the range of 5 to 100 cP. The correction isconsidered rigorous because the Reynolds Number must be determined,which requires the determination of the measured fluid's density. If thedensity of the measurement fluid is not measured directly, such as witha densitometer, the density must be approximated, such as by a saltcontent of the base fluid 100. Further, determination of a Reynoldsnumber requires knowledge of the measured fluid's viscosity, anapproximation of which may only be known. Thus, determination of thecorrection factor may involve iteration and possibly other knownnumerical methods.

The simple correction involves correlating the performance of the RMD400 with a known viscosity of the fluid by unitizing a simple additionor subtraction factor, such as 1.15. Therefore, the simple correctionmay be reflected in Equation 9, below:

$\begin{matrix}{{\mu_{app} = K_{1}}{\frac{\Delta\; P}{Q} - 1.15}} & {{Euation}\mspace{14mu} 9}\end{matrix}$

A further correction may also be applied to correct for fluctuations inflow rate due to, for example, debris in the measured fluid orrestrictions in the measuring tube 410 as a result thereof. Theshort-term perturbations in flow rate that may be experience may becorrected using Equation 10, below:

$\begin{matrix}{{\mu_{app} = K_{1}}{{\frac{\Delta\; P}{Q}\left( \frac{Q_{ref}}{Q} \right)^{n - 1}} - 1.15}} & {{Equation}\mspace{14mu} 10}\end{matrix}$

Equation 10 is operable to shift the viscosity from the measured flowrate to the desired flow rate, Q_(ref), using power law fluidassumptions, and n is defined by the following relationship:n=MIN(1,1.77μ⁻⁴³)  Equation 11

Equation 11 may be used to estimate the power law coefficient it, andthe MIN function represents, with respect to Equation 11, that themaximum values of n may not exceed 1.

The viscosity determination described above may be implemented as anapplication stored with and executed by the control unit 520 of the RMD400. As a result, the RMD 400 is capable of determining the viscosity ofthe measured fluid, such as the base fluid 100, the fracturing fluid110, or any other fluid, may be determined with high accuracy.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. For example,implementations of the present disclosure may also be applicable tofluids flowing through pipelines. In order to reduce pumpingrequirements, such as for pumping the fluid up to a particularelevation, a friction reducer may be introduced into the fluid. Thus,implementations of the present disclosure may be used in a mannersimilar to that described above for pipeline applications. Accordingly,other implementations are within the scope of the following claims.

1. A rheology measurement device comprising: a measurement tube; a firstpressure sensor disposed at a first position on the measurement tube; asecond pressure sensor disposed at a second position on the measurementtube; a flow meter disposed at a third position along the measurementtube; a temperature sensor disposed at a fourth location along themeasurement tube; and a control unit interconnected to the first andsecond pressure sensors, the flow meter, and the temperature sensor, thecontrol unit operable to determine a viscosity of a fluid flowingthrough the measurement tube based at least in part on one or moresignals received from the first pressure sensor, the second pressuresensor, the flow meter, and the temperature sensor, wherein thedetermined viscosity is corrected based at least in part on a bendgeometry of the measurement tube.
 2. The rheology measurement deviceaccording to claim 1, wherein at least a portion of the measurement tubeis curved.
 3. The rheology measurement device according to claim 2,wherein the curved portion of the measurement tube comprises 1.5 loops.4. The rheology measurement device according to claim 1 furthercomprising: an inlet tube; and an outlet tube, wherein internaldiameters of the inlet tube, the outlet tube, and the measurement tubeare the same.
 5. The rheology measurement device according to claim 4,wherein a length of the inlet tube corresponds to a length forestablishing a laminar flow of a fluid flowing therein at the firstposition and wherein a length of the outlet tube corresponds to a lengthfor establishing a laminar flow of a fluid flowing therein at the secondposition.
 6. The rheology measurement device according to claim 1,wherein the first and second pressure sensors comprise a pressuretransducer operable to measure a pressure difference of a fluid flowingthrough the measurement tube.
 7. The rheology measurement deviceaccording to claim 1 further comprising a pump operable to pump a fluidthrough the measurement tube.
 8. The rheology measurement deviceaccording to claim 7, wherein the control unit is operable to determinea fluid flow rate through the tube measurement tube via the flow meterand wherein the control unit is operable to control the pump toestablish a flow rate of the fluid through the measurement tube at aselected flow rate.
 9. The rheology measurement device according toclaim 4, wherein the flow meter is one of an electromagnetic flow meter,a coriolis flow meter, an ultrasonic flow meter, a vortex flow meter, aturbine flow meter, or positive displacement flow meter.
 10. Therheology measurement device according to claim 1, wherein the viscosityis determined based at least in part on a shear rate of the fluid at asurface of the measurement tube.
 11. The rheology measurement deviceaccording to claim 10, wherein the viscosity is determined according tothe equation:$\mu = {\mu_{app}\left( \frac{\gamma}{\gamma_{w}} \right)}$ where μ isthe viscosity, μ_(app) is the apparent viscosity, γ is a selected shearrate, and γ_(w) is the shear rate of the fluid at a surface of themeasurement tube.
 12. The rheology measurement device according to claim10, wherein the fluid is a non-Newtonian fluid.
 13. The rheologymeasurement device according to claim 1, wherein the determinedviscosity is corrected based on one or more signals received from thetemperature sensor.
 14. The rheology measurement device according toclaim 1, wherein the viscosity is corrected based at least in part on apressure difference of the fluid flowing through the measurement tubeand a flow rate of the fluid flowing through the measurement tube. 15.The rheology measurement device according to claim 14, wherein theviscosity is corrected according to the equation:$\mu_{app} = {K_{morgan}K_{1}\frac{\Delta\; P}{Q}}$ where K_(morgan)comprises a constant based on a Reynold's number of the fluid, K₁comprises a meter factor, ΔP is the pressure difference of the fluidflowing through the measurement tube, and Q is the flow rate of thefluid flowing through the measurement tube.
 16. The rheology measurementdevice according to claim 15, wherein K_(morgan) is determined throughan iterative calculation.
 17. The rheology measurement device accordingclaim 14, wherein the viscosity is corrected according to the equation:$\mu_{app} = {{K_{1}\frac{\Delta\; P}{Q}} - 1.15}$ where K₁ comprises ameter factor, ΔP is the pressure difference of the fluid flowing throughthe measurement tube, and Q is the flow rate of the fluid flowingthrough the measurement tube.
 18. A method for measuring a rheologicalproperty of a fluid comprising: passing a fluid flow through ameasurement tube at a selected flow characteristic; determining apressure of the fluid flow at a first location along the measurementtube; determining a pressure of the fluid flow at a second locationalong the measurement tube; determining a pressure difference of thefluid flow between the first and second locations; and determining aviscosity of the fluid passing through the measurement tube based atleast in part on the pressure difference and at least one geometricalproperty of the measurement tube.
 19. The method according to claim 18further comprising: controlling a flow rate of the fluid flow throughthe measurement tube to maintain the selected flow characteristic. 20.The method according to claim 18, wherein the selected flowcharacteristic is a shear rate of the fluid at a surface of themeasurement tube.
 21. The method according to claim 18, wherein thegeometrical property of the measurement tube comprises one of: a lengthof the measurement tube; a diameter of the measurement tube; a shapefactor of the measurement tube; or a bend geometry of the measurementtube.
 22. A rheology measurement device comprising: a measurement tube;a first pressure sensor disposed at a first position on the measurementtube; a second pressure sensor disposed at a second position on themeasurement tube; a flow meter disposed at a third position along themeasurement tube; a temperature sensor disposed at a fourth locationalong the measurement tube; and a control unit interconnected to thefirst and second pressure sensors, the flow meter, and the temperaturesensor, the control unit operable to determine a viscosity of a fluidflowing through the measurement tube based at least in part on one ormore signals received from the first pressure sensor, the secondpressure sensor, the flow meter, and the temperature sensor, wherein thecontrol unit is operable to determine the viscosity based at least inpart on a shear rate of the fluid at a surface of the measurement tube.23. The rheology measurement device according to claim 22, wherein theviscosity is determined according to the equation:$\mu = {\mu_{app}\left( \frac{\gamma}{\gamma_{w}} \right)}$ where μ isthe viscosity, μ_(app) is the apparent viscosity, γ is a selected shearrate, and γ_(w) is the shear rate of the fluid at a surface of themeasurement tube.
 24. The rheology measurement device according to claim22, wherein the fluid is a non-Newtonian fluid.
 25. A rheologymeasurement device comprising: a measurement tube; a first pressuresensor disposed at a first position on the measurement tube; a secondpressure sensor disposed at a second position on the measurement tube; aflow meter disposed at a third position along the measurement tube; atemperature sensor disposed at a fourth location along the measurementtube; and a control unit interconnected to the first and second pressuresensors, the flow meter, and the temperature sensor, the control unitoperable to determine a viscosity of a fluid flowing through themeasurement tube based at least in part on one or more signals receivedfrom the first pressure sensor, the second pressure sensor, the flowmeter, and the temperature sensor, wherein the determined viscosity iscorrected based on one or more signals received from the temperaturesensor.